Question

These questions are linked, specifically 6 & 7. Please help & explain, especially #7.

5. Draw and name all the geometrical isomers of Co(NH3)4(NO2)2 6. Draw all the geometrical isomers of Pt(CN)2Br2(H20)2 7. Which one of the geometrical isomers in question 6 exhibit optical isomerism? Draw the two optical isomers.

Answer 1

The possible spatial arrangements of the complex are written by writing the diagonal ligands as one pair. The only possible distinct arrangements are those which will not repeat the same pairs in a group.

For example, In problem 6, see the possible arrangements, written in the attached image. Any other arrangement will give one of these 5 groupings.

5. In the complex there are only 2 possible geometrical isomers as shown below. Also, There is plane of symmetry in both of them and both are optically inactive.

The -cis and -trans forms are decided based on the relative position of (NO₂) group i.e. named 'b' in the diagram.

Co M and and N0,b 5. Let EHN Ma2 Co (NM)4(N)2 1 then, a a Pas a a a a Cis-is emer Trans- isomer (aa, ab, ab) (aa, aa, bb) eme eb ine uill otner ansangament grouping eny Any turo these

6 &7.

There are 5 possible geometrical isomers and only 2 of them lack plane of symmetry (PoS) therefore they are optical isomers.

Total 6 ligands 6. Let the be, houps CNE a BrE b bthahedal and 20E C geomery metal be Pt M and tyteMa, b2 thon the complex is The possible pahial arranguments ane Pos (b ) a b a M a a a Б C M. a Ь a C These are (ac, ac, bb) (a ab, be), (ab, ab, cc), (be, aa, bo), (bb, aa,cc) ymmehy wniten, is PoS Plane Now, enly the uing in which dishinct pai are will not chiral centes will haue there ymumetay ab ene as shoun haue plane Thrapere are ophical isomers v) and Изо N C CN Br and 20 Br Нао N C

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